Detailed studies of tumor-host immune interactions in animals and humans with sarcomas are being performed in an attempt to develop new immunodiagnostic and immunotherapeutic techniques for diagnosis and treatment of these tumors. Immune response to murine sarcomas has been extensively evaluated and both tumor-specific and fetal antigens have been identified. Fetal antigens have been identified on human osteogenic sarcomas and these antigens are now being characterized. Attempts are being made to develop adoptive immunotherapeutic techniques utilizing transfer of cells from xenogeneic species to humans with cancer.